Technical Field
The technical field relates to a plug-in power adapter, and more particularly to a power adapter capable of screwing and connecting a conventional lamp holder to electrically conduct a power supply. During use, the plug-in power adapter is electrically connected to a power cable of an electric appliance to supply electric power to other electric appliances. In the meantime, the power cable connected to the power adapter is clamped securely to prevent the power cable from being separated from the power adapter.
Description of the Related Art
With reference to FIG. 1 for a conventional lamp holder 10, the lamp holder 10 is installed at the middle of the inner top of a lampshade 11 and electrically connected to an external power supply (such as the mains power) by an upwardly extended power cable 12, and the lampshade 11 is generally embedded into a board 13 disposed at a high position. During use, the lamp holder 10 is provided for screwing a head portion of a bulb 14 therein. When the power supply is turned on, the bulb 14 will emit light in a direction from top to bottom. Since the lamp is installed at a high position, such lamp is called a “down light”.
The lamp holder 10 is a common conventional electric component comprising a screwing portion for receiving and connecting the head portion of the bulb 14, so that the screwing portion of the lamp holder 10 is electrically connected to the power cable 12 for supplying electric power to the bulb 14 at appropriate time. The lamp holder 10 has two main functions including the functions of connecting the bulb 14 and supplying power to the bulb 14. The lamp holder 10 may be installed at a high position to provide a “down light” mode or used in other modes as a ceiling lamp, a table lamp, a desk lamp or a floor lamp.
The bulb 14 may be a light emitting element. The bulb 14 at an early stage adopts tungsten to emit light (or uses tungsten as the light emitting element), and the bulb 14 is generally in a spherical shape and has a screw head formed at a connecting position and screwed into a screwing portion of the lamp holder 1, so that the spherical portion is suspended outside the lamp holder 10 as shown in FIG. 1. As technology advances, various different types of light emitting elements are developed, and they are not limited to tungsten for emitting light. In recent years, LED is developed to produce various different types of light emitting elements and their appearance is no longer limited to the spherical shape. For example, a flat LED light emitting element is often applied for projecting light from a high position.
1. With reference to FIG. 1 for a down light, the down light is extensively used as a lamp in many families. To save power, the flat LED light emitting element is used, and the most convenient arrangement resides on that users need not to remove the lampshade 11 to access the same area of an opening surface of the lampshade 11 in order to install the flat LED light emitting element, so that the flat LED light emitting element can be installed in the opening surface of the lampshade 11 securely to replace the aforementioned down light at the same position and achieve the same effect of projecting light downward. Such modification saves lots of labor and cost. However, the way of electrically conduct the LED light emitting element installed in the opening surface to a power supply is a skill of the modification. In general, a connecting wire of the LED light emitting element is connected directly to the power cable 12, but such connection may have the drawbacks of electric shocks and unintentional disconnection or detachment at the wire connecting position after a long time of use. Obviously, the prior art requires improvements.